Dengue, malaria and leptospirosis cases are rising this monsoon. Here's what doctors want you to know

India is witnessing the expected seasonal rise in vector-borne and water-borne diseases with the onset of the south-west monsoon, although national surveillance suggests transmission began earlier than usual this year.

According to the National Centre for Vector Borne Disease Control (NCVBDC), 6,927 dengue cases were reported by the end of February 2026, indicating an unusually early start to the dengue season compared with previous years.

At the state level, the burden is rising steadily. Mumbai has reported an 18.2 per cent increase in malaria cases, from 3,115 cases in 2025 to 3,681 cases in 2026, alongside a rise in dengue notifications. In Jharkhand's East Singhbhum district, authorities recently confirmed 101 new malaria cases, taking the outbreak death toll to six.

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Meanwhile, clinicians in Mumbai are reporting an increase in leptospirosis, particularly following heavy rainfall and flooding, with experts warning that it is frequently mistaken for viral fever, dengue or malaria, delaying treatment.

Hospital physicians also report that dengue remains the leading cause of acute febrile illness during the monsoon, followed by respiratory and gastrointestinal viral infections, while overlapping symptoms and occasional co-infections are making diagnosis more challenging.

Overall, current surveillance highlights the need for early testing, prompt diagnosis and strengthened vector-control measures as monsoon-related infections continue to rise across India.

Hospitals are seeing more patients with acute febrile illnesses

According to Dr Shubhra Gupta, Senior Consultant, Medicine, RG Hospitals, Delhi, hospitals are already witnessing a noticeable increase in seasonal infections.

"This monsoon, hospitals are witnessing a noticeable increase in patients presenting with acute febrile illnesses, with dengue, malaria, leptospirosis and seasonal viral fevers accounting for the majority of admissions."

"What makes this season particularly challenging is that these infections often begin with similar symptoms: fever, headache, body aches and fatigue, making clinical evaluation and timely laboratory testing essential for accurate diagnosis."

Dr Gupta says delayed presentation is increasing the risk of severe complications.

"We are also seeing patients arriving later in the course of illness, increasing the risk of complications such as dehydration, thrombocytopenia in dengue, severe malaria, or kidney and liver involvement in leptospirosis."

"Another emerging concern is the possibility of co-infections, which can complicate treatment and recovery."

While most viral fevers remain self-limiting, Dr Gupta advises people not to ignore warning signs.

"Persistent high fever, bleeding, breathlessness, altered consciousness or reduced urine output should never be ignored."

Early diagnosis can prevent severe complications

Dr Gupta stresses that prevention and timely medical care remain the best defence against monsoon illnesses.

"Preventive measures such as avoiding mosquito breeding, using protective clothing and repellents, maintaining good hygiene and seeking medical attention early remain the most effective ways to reduce disease burden."

"From an Internal Medicine perspective, early diagnosis, close monitoring and evidence-based management continue to be the key factors in preventing severe outcomes and ensuring better patient recovery during the monsoon season."

Viral fever, dengue and malaria continue to dominate

According to Dr Chirag Tandon, Director, Department of Internal Medicine, Shardacare - Medicity, viral fevers remain the most common diagnosis, but mosquito-borne and water-borne diseases are also increasing.

"This monsoon, the hospital is witnessing a surge in viral fever, dengue and malaria patients, with a few instances of leptospirosis too."

"Viral fevers continue to top the chart, but the clinic is getting an increasing number of patients presenting with mosquito-borne and water-borne illnesses due to the accumulation of stagnant water and poor sanitation."

He says these illnesses often begin with symptoms that resemble a routine viral infection.

"It may start as a non-specific fever, headache, body pain and weakness that may seem as common as any seasonal viral infection, and hence it becomes important for all patients to get an early check-up."

"Reports from other hospitals across India too show a growing prevalence of seasonal fevers during the monsoon."

When should you see a doctor?

Dr Tandon says people should not delay medical attention if symptoms persist or worsen.

"A patient should visit the clinic if the fever is not subsiding beyond two or three days, or there is associated severe body pain, vomiting, shortness of breath, reduced urine output, bleeding, disorientation or excessive fatigue."

"Blood tests will help diagnose the infection in the initial stages and facilitate appropriate treatment. Avoid self-medication, especially using antibiotics without the advice of a doctor."

Simple precautions can reduce your risk

Dr Tandon recommends adopting basic preventive measures throughout the monsoon.

"Small preventive steps could make a world of difference. Use repellents and eliminate sources of stagnant water to avoid mosquito breeding, wear footwear when walking through waterlogged areas, drink safe water, wash your hands frequently, and do not ignore persistent fever during the monsoon."

"Timely detection and early treatment will prove to be the most crucial factors in preventing complications."